I do not know the true original source of this information. I found this handwritten in my grandmother's journal and found it too charming not to share. Enjoy!
JANUARY Carnation Striped - do not refuse me. Pink - sweetness. Purple - capriciousness. Red - admiration. White - innocence. Yellow - disdain.
FEBRUARY Violet Blue - faithfulness. Yellow - rural happiness. Sweet - modesty. Flame - watchfulness.
MARCH Jonquil - I desire a return of affection
APRIL Sweet Pea - delicate pleasures, departure
MAY Lily of the Valley - sweetness, humility
JUNE Rose Single bloom - simplicity. Bud - youth and beauty. Full bloom - I love you. Full bloom over 2 buds - secrecy. Pink - perfect happiness. Coral - pleasure. Red - love, friendship, passion. White - purity. Yellow - jealousy or regard.
JULY Larkspur Pink - fickleness. Purple - haughtiness.
AUGUST Gladiolus - strength of character
SEPTEMBER Aster - daintiness
OCTOBER Calendula - wise and cheerful spirit
NOVEMBER Chrysanthamum - cheerfulness. Red - I love you. Yellow - slighted love. White - truth
DECEMBER Poinsetta - strength and rejoicing OR Narcissus - egotism or if double - female ambition